Semiconductive ceramic composition

ABSTRACT

A semiconductive ceramic composition capable of permitting its resistance-temperature characteristics and resistance to be controlled as desired and a firing temperature of the composition to be lowered to a degree sufficient to facilitate the mass-production at a low cost. The composition contains a main component consisting of SrO, PbO and TiO 2  and is subjected to firing in an oxidizing atmosphere. The composition may contain at least one of SiO 2  and M as a minor component. A variation in amount of the main and minor components permits characteristics and properties of the composition to be varied as desired.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a semiconductive ceramic composition adaptedto be used for a sensor, a functional element such as a current limiteror a rush current restrictor, or the like, and more particularly to asemiconductive ceramic composition which mainly consists of SrO, PbO andTiO₂ and exhibits PTC (Positive Temperature Coefficient Thermistor)characteristics having a positive temperature coefficient, NTC (NegativeTemperature Coefficient Thermistor) characteristics having a negativetemperature coefficient, so-called V-type PTC characteristics havingboth positive and negative temperature coefficients, CTR (CriticalTemperature Resistor) characteristics wherein resistance is abruptlydecreased at a certain temperature region, or the like.

2. Description of the Prior Art

A conventional semiconductive ceramic composition having a positivetemperature coefficient mainly consists of barium titanate BaTiO₃. Sucha conventional composition has a high firing temperature when anadditive other than an additive for semiconductivity is not addedthereto, so that in its specific resistance or resistivity-temperaturecharacteristic curve, resistance rises at a gentle gradient, resultingin failing to have a V-type resistivity-temperature characteristic curvehaving a negative resistance-temperature coefficient region of a flatshape.

There is also proposed a PbTiO₃ composition having an additive forsemiconductivity added thereto for the purpose of substituting Sr or Cafor a part of Pb. It is known in the art that firing or burning of thecomposition in air causes an increase in resistance of the composition,resulting in failing to provide the composition with low resistancerequired to function as a semiconductor, however, the firing in an argonatmosphere satisfactorily provides the composition with desired lowresistance and provides a positive temperature coefficient thermistor ofa high curie point. Unfortunately, the composition thus fired in an Aratmosphere is increased in resistance in normal use in air, resulting inthe characteristics being unstable.

A negative temperature coefficient thermistor is mainly formed oftransition metals such as Mn, Ni, Co and the like and has a B constantup to about 4000 (-α: 4 to 5%), so that it is highly difficult to vary agradient of a resistivity-temperature characteristic curve over a widerange. Also, it has another disadvantage that adjustment of theresistance leads to a variation of the B constant. In the negativetemperature coefficient thermistor, a variation of the resistance with atemperature is not linear in a logarithmic graph showingresistancetemperature characteristics of the semiconductive ceramiccomposition, accordingly, use of the thermistor requires a circuit torender the variation linear.

Further, the negative temperature coefficient thermistor isprogressively decreased in resistance due to its own heat release whenan overvoltage is applied thereto, resulting in being broken. In view ofthe above, an element is proposed which is formed by thermally joining anegative temperature coefficient element used for restricting an inrushcurrent when a power supply is switched on and a positive temperaturecoefficient element for preventing flowing of an overcurrent when anyabnormality together so that V-type temperature characteristics may beexhibited to rapidly carry out both inrush current restriction andovercurrent prevention.

In addition, a critical temperature resistor is mainly formed of V₂ O₅,basic oxide and the like, resulting in a reduction treatment and aquenching treatment being required to lead to a failure in stablemanufacturing of the resistor. Also, the critical temperature resistoris in the form of a bead-like shape and adapted to use a Pt wire or thelike as a lead wire, thus, its configuration is subject to restrictionto cause its cost to be increased. Also, shifting of a point at whichresistance of the resistor is abruptly varied is limited within a rangeas narrow as 50° to 80° C. Further, a restriction on manufacturing ofthe critical temperature resistor fails to form it into a bulky shape,so that it may not be used under a high voltage.

The inventors, as a result of research in view of the foregoing,developed a semiconductive ceramic composition which is free of Bairrespective of having an ABO₃ perovskite structure by selecting Sr andPb on an A site and which further exhibits PTC characteristics of arelatively large negative temperature coefficient (NTC region) withoutany additive, as disclosed in Japanese Patent Application Laying-OpenPublication No. 280401/1988.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoingdisadvantage of the prior art while, as a result of our research, noticehas been taken of the fact that a variation in composition of main andminor components in the above-described composition developed by usprovides a semiconductive ceramic composition which permitsresistance-temperature characteristics and resistance of the compositionto be controlled additionally the a firing temperature of thecomposition can be lowered and the firing of the composition in anoxidizing atmosphere provides a ceramic of stable characteristics.

Accordingly, it is an object of the present invention to provide asemiconductive ceramic composition which is capable of controlling itsresistance-temperature characteristics and/or resistance as desired.

It is another object of the present invention to provide asemiconductive ceramic composition which is capable of significantlylowering its firing temperature.

It is a further object of the present invention to provide asemiconductive ceramic composition which is capable of providing aceramic of stable characteristics.

It is still another object of the present invention to provide asemiconductive ceramic composition which is capable of possessing NTCcharacteristics, V-type PTC characteristics, PTC characteristics or CTRcharacteristics as desired.

It is yet another object of the present invention to provide asemiconductive ceramic composition which is capable of permitting itsNTC characteristics, V-type PTC characteristics, PTC characteristics orCTR characteristics to be varied as desired.

It is even another object of the present invention to provide asemiconductive ceramic composition which is capable of exhibitingvarious resistance-temperature characteristics and varying thecharacteristics over a wide range.

It is still a further object of the present invention to provide asemiconductive ceramic composition which is capable of rapidly andpositively exhibiting V-type characteristics.

It is yet a further object of the present invention to provide asemiconductive ceramic composition which is capable of being readilymanufactured.

It is even a further object of the present invention to provide asemiconductive ceramic composition which is capable of being formed intovarious sizes and/or configurations.

In accordance with the present invention, a semiconductive ceramiccomposition is provided. The composition comprises Sr of 0.05 to 0.95mol based on SrO, Pb of 0.05 to 0.85 mol based on PbO, Ti of 0.90 to 2.0mol based on TiO₂ and R of 0.001 to 0.3 mol based on its oxide. R is atleast one material selected from the group consisting of rare earthelements, Bi, V, W, Ta, Nb and Sb. The amounts of rare earth elementsexcept Ce, Bi and Sb are based on 1/2(R₂ O₃), the amounts of V, Ta andNb are based on 1/2(R₂ O₅) and the amounts of Ce and W are based on RO₂and RO₃, respectively. The composition is subjected to firing in anoxidizing atmosphere.

The semiconductive ceramic composition of the present invention mayfurther comprise SiO₂ added in an amount of 0.001 to 30 wt%.

The composition of the present invention may further comprise M addedthereto, which is at least one material selected from the groupconsisting of Mn, Cu, Cr, Ni, Fe, Co, Ru, Os, Ge, Hf, P, Sb, V, Mg, Zn,W, Al, Mo, In, Ga, Nb, Ta, Bi, Sc, rare earth elements, Th, Na, K, Li,B, Ag, Cs and Rb. M is added in amounts of 0.00001 to 1.2 wt% except Aland W, and Al and W is added in amounts of 0.00001 to 8 wt%.

SiO₂ and M may be added together to the composition.

In the present invention, SrO and PbO are replaced in amounts of 0.001to 0.3 mol with at least one of BaO and CaO.

The semiconductive ceramic composition of the present invention whichcontains SrO, PbO and TiO₂ as its main component as described aboveprovides a ceramic having PTC characteristics, V-type PTCcharacteristics, NTC characteristics, or CTR characteristics as desired.An increase in TiO₂ permits specific resistance or resistivity of thecomposition to be controlled from a low level to a high level withoutsignificantly varying a gradient of resistance-temperaturecharacteristics, resulting in providing a ceramic element which iscapable of meeting any resistance requirements. SiO₂ contributes tolowering of a temperature at which the composition starts to possesssemiconductivity (hereinafter referred to as "semiconductivity startingtemperature") and changes characteristics of the composition from V-typePTC characteristics to characteristics approaching to CTRcharacteristics. Addition of M enhances PTC characteristics and NTCcharacteristics. Also, substitution of BaO and CaO for a part of SrO andPbO enhances PTC characteristics and permits a particle size of thecomposition fired or sintered to be uniform. Further, concurrent orcombined addition of additives exhibiting different functions to thecomposition provides it with features of the respective additives.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and many of the attendant advantages of thepresent invention will be readily appreciated as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings; wherein:

FIGS. 1 to 5 each are a graphical representation showing aresistivity-temperature characteristic curves of a semiconductiveceramic composition according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, a semiconductive ceramic composition according to the presentinvention will be described hereinafter with reference to the followingexample.

Example

Starting materials for various semiconductive ceramic compositions wereselected from SrCO₃, PbO, Y₂ O₃, TiO₂, CaCO₃, La₂ O₃, CeO₂, Nd₂ O₅, Sm₂O₃, Dy₂ O₃, Gd₂ O₃, V_(2O) ₃, Bi₂ O₃, WO₃, Ta₂ O₅, Nb₂ O₅, Sb₂ O₃,MnCO₃, CuO, Cu₂ O₃, Cr₂ O₃, Li₂ CO₃, Th₂ O₃, Sc₂ O₃, Fe(NO₃)₃, A1₂ O₃,P₂ O₅, CoO, BaCO₃, ZnO, MgCO₃, B₂ O₃, NiO, Na₂ O, Ga, In, T1, Rb₂ O, Ca₂O, Ag, Ru₂ O₃, Os₂ O₃, Ge, 2, MoO₃ and K₂ O and weighed to preparesemiconductive ceramic compositions shown in TABLES 1 to 6. The amountsof minor components M shown in the tables were based on their elements.The selected and weighed materials were then placed in a polyethylenepot mill charged with agate beads and subjected to wet mixing for 20hours, resulting in being powdered. Then, each of the soobtained powdermaterials was subjected to hydration and drying followed by calcinationat a temperature of 800° to 1100° C. for 2 hours.

The material calcined was coarsely grained and then water-ground forabout 20 hours in the pot mill described above, followed by dehydrationand drying.

Subsequently, polyvinyl alcohol (PVA) was added to the dried material tolead to granulation of the material, which was then subjected to shapingat a pressure of about 2 ton/cm² by means of a hydraulic pressingmachine, resulting in a disc of 16.5 mm in diameter and 3.5 mm inthickness. The so-formed disc was then subjected to firing or burningfor 2 hours at a temperature of 1150° to 1300° C. in a batch oven of anoxidizing atmosphere, resulting in each of the semiconductive ceramiccomposition being obtained in the form of a disc-like shape havingdimensions of 14 mm in diameter and 2.5 mm in thickness.

The so-prepared semiconductive ceramic composition specimens each wereformed on both surfaces thereof with electrodes of In-Ga alloy, so thatspecific resistance or resistivity at 20° C., minimum resistivity andresistance-temperature characteristics were measured with respect toeach specimen.

The results were as shown in TABLES 1 to 6 and FIGS. 1 to 5. In thetables, specimens with which an asterisk (*) is marked are not includedin the scope of the present invention. A temperature coefficient α isindicated by the following equation: ##EQU1## Also, a curie point Tcindicates a temperature at an intersection of extensions from linearsections on both sides of an inflection point.

                                      TABLE 1                                     __________________________________________________________________________                          Specific Resistance                                                                         Temperature                                                                           Curie                             Main Components       Ω-cm    Coefficient                                                                           Point                             Specimen                                                                           Molar Ratio of Each Component                                                                  ρ.sub.20                                                                         ρ.sub.min                                                                        %/°C.                                                                          °C.                        No.  SrO PbO 1/2(Y.sub.2 O.sub.3)                                                               TiO.sub.2                                                                         (at 20° C.)                                                                   (minimum)                                                                            -α                                                                          α                                                                           Tc                                __________________________________________________________________________    *1   0.497                                                                             0.497                                                                             0.006                                                                              0.88                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                 2   0.497                                                                             0.497                                                                             0.006                                                                              0.90                                                                              2.0 × 10.sup.7                                                                 1.1 × 10.sup.6                                                                 3.19                                                                              5.00                                                                              120                                3   0.497                                                                             0.497                                                                             0.006                                                                              0.95                                                                                1 × 10.sup.4                                                                 2.9 × 10.sup.2                                                                 3.50                                                                              6.4 130                                4   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5 136                                5   0.497                                                                             0.497                                                                             0.006                                                                              1.2 1.2 × 10.sup.3                                                                   9 × 10.sup.1                                                                 3.05                                                                              4.5 142                                6   0.497                                                                             0.497                                                                             0.006                                                                              1.5 2.6 × 10.sup.5                                                                   9 ×  10.sup.4                                                                3.14                                                                              4.1 140                                7   0.497                                                                             0.497                                                                             0.006                                                                              1.0 3.8 × 10.sup.7                                                                 2.2 × 10.sup.5                                                                 2.97                                                                              4.10                                                                              160                               *8   0.497                                                                             0.497                                                                             0.006                                                                              2.3 >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *9   0.485                                                                             0.485                                                                             0.03 0.88                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                10   0.485                                                                             0.485                                                                             0.03 0.90                                                                              >10.sup.9                                                                              5 × 10.sup.5                                                                 14.2                                                                              1.20                                                                              145                               11   0.485                                                                             0.485                                                                             0.03 0.95                                                                              >10.sup.9                                                                              3 × 10.sup.4                                                                 13.8                                                                              0.10                                                                              154                               12   0.485                                                                             0.485                                                                             0.03 1.00                                                                              >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                                                                              142                               13   0.485                                                                             0.485                                                                             0.03 1.2   1 × 10.sup.9                                                                 1.0 × 10.sup.3                                                                 11.2                                                                              1.31                                                                              130                               14   0.485                                                                             0.485                                                                             0.03 1.5 >10.sup.9                                                                              2 × 10.sup.4                                                                 12.8                                                                              1.05                                                                              135                               15   0.485                                                                             0.485                                                                             0.03 2.0 >10.sup.9                                                                              5 × 10.sup.5                                                                 13.3                                                                              1.12                                                                              135                               *16  0.485                                                                             0.485                                                                             0.03 2.3 >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *17  0.4998                                                                            0.4998                                                                            0.0005                                                                             1.00                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                18   0.4995                                                                            0.4995                                                                            0.001                                                                              1.00                                                                              1.2 × 10.sup.5                                                                 5.1 × 10.sup.3                                                                 2.21                                                                              7.1 135                               19   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5 136                               20   0.495                                                                             0.495                                                                             0.01 1.00                                                                                1 × 10.sup.6                                                                 2.5 × 10.sup.2                                                                 8.0 1.8 135                               21   0.485                                                                             0.485                                                                             0.03 1.00                                                                              >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                                                                              142                               22   0.45                                                                              0.45                                                                              0.10 1.00                                                                              >10.sup.9                                                                            5.4 × 10.sup.3                                                                 15.0                                                                              1.10                                                                              138                               23   0.35                                                                              0.35                                                                              0.30 1.00                                                                              >10.sup.9                                                                              6 × 10.sup.5                                                                 18.2                                                                              1.03                                                                              132                               *24  0.325                                                                             0.325                                                                             0.35 1.00                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *25  0.4998                                                                            0.4998                                                                            0.0005                                                                             0.95                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                26   0.4995                                                                            0.4995                                                                            0.001                                                                              0.95                                                                                5 × 10.sup.6                                                                 3.5 × 10.sup.4                                                                 3.12                                                                              5.7 132                               27   0.497                                                                             0.497                                                                             0.006                                                                              0.95                                                                                1 × 10.sup.4                                                                 2.4 × 10.sup.2                                                                 3.50                                                                              6.4 130                               28   0.485                                                                             0.485                                                                             0.03 0.95                                                                              >10.sup.9                                                                              3 × 10.sup.4                                                                 13.8                                                                              1.10                                                                              154                               29   0.35                                                                              0.357                                                                             0.30 0.95                                                                              >10.sup.9                                                                              7 × 10.sup.6                                                                 13.5                                                                              1.05                                                                              145                               *30  0.325                                                                             0.325                                                                             0.35 0.95                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *31  0.4998                                                                            0.4992                                                                            0.0005                                                                             1.2 >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                32   0.4995                                                                            0.4995                                                                            0.001                                                                              1.2 5.6 × 10.sup.5                                                                 3.2 × 10.sup.3                                                                 2.65                                                                              3.9 141                               33   0.497                                                                             0.497                                                                             0.006                                                                              1.2 1.2 × 10.sup.3                                                                   9 × 10.sup.1                                                                 3.05                                                                              4.5 142                               34   0.485                                                                             0.485                                                                             0.03 1.2   1 × 10.sup.9                                                                   1 × 10.sup.3                                                                 11.2                                                                              1.31                                                                              130                               35   0.35                                                                              0.35                                                                              0.30 1.2 >10.sup.9                                                                              5 × 10.sup.5                                                                 12.6                                                                              1.14                                                                              135                               *36  0.325                                                                             0.325                                                                             0.35 1.2 >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *37  0.094                                                                             0.90                                                                              0.006                                                                              1.00                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                38   0.144                                                                             0.85                                                                              0.006                                                                              1.00                                                                              >10.sup.9                                                                            3.2 × 10.sup.5                                                                 3.34                                                                              7.2 380                               39   0.394                                                                             0.60                                                                              0.006                                                                              1.00                                                                              2.2 × 10.sup.5                                                                 2.1 × 10.sup.2                                                                 4.06                                                                              5.5 200                               40   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5 136                               41   0.597                                                                             0.40                                                                              0.006                                                                              1.00                                                                              3.5 × 10.sup.3                                                                 1.1 × 10.sup.2                                                                 3.43                                                                              5.3  78                               42   0.944                                                                             0.05                                                                              0.006                                                                              1.00                                                                              --     5.6 × 10.sup.5                                                                 3.33                                                                              6.0 122                               *43  0.964                                                                             0.03                                                                              0.006                                                                              1.00                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *44  0.094                                                                             0.90                                                                              0.006                                                                              0.95                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                45   0.144                                                                             0.85                                                                              0.006                                                                              0.95                                                                              >10.sup.9                                                                            5.4 × 10.sup.5                                                                 3.60                                                                              7.2 378                               46   0.497                                                                             0.497                                                                             0.006                                                                              0.95                                                                                1 × 10.sup.4                                                                 2.4 × 10.sup.2                                                                 3.50                                                                              6.4 130                               47   0.944                                                                             0.05                                                                              0.006                                                                              0.95                                                                              --       3 × 10.sup.2                                                                 3.4 6.0 -103                              *48  0.964                                                                             0.03                                                                              0.006                                                                              0.95                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *49  0.094                                                                             0.90                                                                              0.006                                                                              1.2 >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                50   0.144                                                                             0.85                                                                              0.006                                                                              1.2 >10.sup.9                                                                              1 × 10.sup.5                                                                 3.32                                                                              5.2 377                               51   0.497                                                                             0.497                                                                             0.006                                                                              1.2 1.2 × 10.sup.3                                                                   9 × 10.sup.1                                                                 3.12                                                                              4.5 -90                               52   0.944                                                                             0.05                                                                              0.006                                                                              1.2 --     .sup.  -- × 10.sup.11                                                              5.5 --                                *53  0.964                                                                             0.03                                                                              0.006                                                                              1.2 >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *54  0.07                                                                              0.90                                                                              0.03 1.00                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                55   0.12                                                                              0.85                                                                              0.03 1.00                                                                              >10.sup.9                                                                              4 × 10.sup.6                                                                 12.8                                                                              1.33                                                                              380                               56   0.394                                                                             0.60                                                                              0.03 1.00                                                                              >10.sup.9                                                                              3 × 10.sup.5                                                                 14.3                                                                              1.12                                                                              220                               57   0.497                                                                             0.497                                                                             0.03 1.00                                                                              >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                                                                              142                               58   0.597                                                                             0.40                                                                              0.03 1.00                                                                                1 × 10.sup.8                                                                 1.2 × 10.sup.3                                                                 15.2                                                                              1.10                                                                               80                               59   0.944                                                                             0.05                                                                              0.03 1.00                                                                              --     5.9 × 10.sup.5                                                                 13.7                                                                              1.08                                                                              -130                              *60  0.964                                                                             0.03                                                                              0.03 1.00                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *61  0.094                                                                             0.90                                                                              0.03 0.95                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                62   0.144                                                                             0.85                                                                              0.03 0.95                                                                              >10.sup.9                                                                              4 × 10.sup.5                                                                 12.9                                                                              1.05                                                                              380                               63   0.497                                                                             0.497                                                                             0.03 0.95                                                                              >10.sup.9                                                                              3 × 10.sup.4                                                                 13.8                                                                              1.10                                                                              154                               64   0.944                                                                             0.005                                                                             0.03 0.95                                                                              --       2 × 10.sup.5                                                                 11.5                                                                              1.15                                                                              -128                              65   0.964                                                                             0.03                                                                              0.03 0.95                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                *66  0.07                                                                              0.90                                                                              0.03 0.95                                                                              >10.sup.9                                                                            >10.sup.9                                                                            --  --  --                                67   0.12                                                                              0.85                                                                              0.03 1.2 >10.sup.9                                                                              3 × 10.sup.5                                                                 10.5                                                                              1.10                                                                              381                               68   0.497                                                                             0.497                                                                             0.03 1.2   1 × 10.sup.9                                                                   1 × 10.sup.3                                                                 11.2                                                                              1.31                                                                              130                               69   0.944                                                                             0.05                                                                              0.03 1.2 --       5 × 10.sup.5                                                                 12.8                                                                              1.18                                                                              -130                              70   0.964                                                                             0.03                                                                              0.03 1.2 >10.sup.9                                                                            > 10.sup.9                                                                           --  --  --                                71   0.497                                                                             0.497                                                                             1/2(La.sub.2 O.sub.3)                                                              0.95                                                                              1.2 × 10.sup.4                                                                 3.2 × 10.sup.2                                                                 3.48                                                                              6.2 131                                            0.006                                                            72   0.497                                                                             0.497                                                                             1/2(Nd.sub.2 O.sub.3)                                                              0.95                                                                              3.6 × 10.sup.4                                                                 1.1 × 10.sup.2                                                                 3.56                                                                              6.4 130                                            0.006                                                            73   0.497                                                                             0.497                                                                             1/2(Dy.sub.2 O.sub.3)                                                              0.95                                                                                1 × 10.sup.4                                                                 2.6 × 10.sup.2                                                                 3.20                                                                              6.3 131                                            0.006                                                            74   0.497                                                                             0.497                                                                             1/2(Sm.sub.2 O.sub.3)                                                              0.95                                                                                2 × 10.sup.4                                                                 1.2 × 10.sup.2                                                                 3.18                                                                              6.2 132                                            0.006                                                            75   0.497                                                                             0.497                                                                             1/2(Ta.sub.2 O.sub.5)                                                              0.95                                                                              5.6 × 10.sup.4                                                                 9.8 × 10.sup.1                                                                 3.57                                                                              6.6 130                                            0.006                                                            76   0.497                                                                             0.497                                                                             1/2(Sb.sub.2 O.sub.3)                                                              0.95                                                                              3.7 × 10.sup.4                                                                 5.6 × 10.sup.2                                                                 3.28                                                                              6.5 133                                            0.006                                                            77   0.497                                                                             0.497                                                                             WO.sub.3                                                                           1.2 1.2 × 10.sup.3                                                                   1 × 10.sup.2                                                                 3.04                                                                              4.3 140                                            0.006                                                            78   0.497                                                                             0.497                                                                             1/2(Bi.sub.2 O.sub.3)                                                              1.2 1.3 × 10.sup.3                                                                   9 × 10.sup.1                                                                 3.21                                                                              4.6 141                                            0.006                                                            79   0.497                                                                             0.497                                                                             1/2(V.sub.2 O.sub.5)                                                               1.2 1.1 × 10.sup.3                                                                 1.3 × 10.sup.2                                                                 3.02                                                                              4.5 144                                            0.006                                                            80   0.497                                                                             0.497                                                                             1/2(Nb.sub.2 O.sub.5)                                                              1.2 1.3 × 10.sup.3                                                                 1.9 × 10.sup.1                                                                 3.32                                                                              4.4 142                                            0.006                                                            81   0.497                                                                             0.497                                                                             1/2(Gd.sub.2 O.sub.3)                                                              1.2 1.1 × 10.sup.3                                                                 2.1 × 10.sup.1                                                                 3.01                                                                              4.5 141                                            0.006                                                            __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________                                 Specific                                                               Minor  Resistance    Temperature                        Main Components       Components                                                                           Ω-cm    Coefficient                        Specimen                                                                           Molar Ratio of Each Component                                                                  wt. %  ρ.sub.20                                                                        ρ.sub.min                                                                         %/°C.                                                                          ST*                        No.  SrO PbO 1/2(Y.sub.2 O.sub.3)                                                               TiO.sub.2                                                                         SiO.sub.2                                                                            (at 20° C.)                                                                   (minimum)                                                                            -α                                                                          α                                                                           °C.                 __________________________________________________________________________    *1   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             0      1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5 1200                       *2   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             0.0005 1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5 1200                        3   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             0.001  1.2 × 10.sup.4                                                                 3.4 × 10.sup.2                                                                 3.15                                                                              7.2 1180                        4   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             0.1    1.6 × 10.sup.4                                                                 3.3 × 10.sup.3                                                                 3.33                                                                              7.2 1160                        5   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             0.4    1.2 × 10.sup.4                                                                 3.4 × 10.sup.2                                                                 3.34                                                                              7.1 1160                        6   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             2.0    8.4 × 10.sup.7                                                                 1.1 × 10.sup.5                                                                 35.6                                                                              0   1160                        7   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             5.0    >10.sup.9                                                                            7.0 × 10.sup.3                                                                 26.8                                                                              0   1150                        8   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             15.0   >10.sup.9                                                                            4.6 × 10.sup.3                                                                 22.0                                                                              0   1150                        9   0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             30.0     5 × 10.sup.8                                                                 8.0 × 10.sup.3                                                                 15.0                                                                              0   1150                       *10  0.497                                                                             0.497                                                                             0.006                                                                              1.000                                                                             35.0   melt   --     --  --  --                         *11  0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              0      >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                                                                              1200                       *12  0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              0.0005 >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                                                                              1200                       13   0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              0.001  >10.sup.9                                                                              1 × 10.sup.3                                                                 13.6                                                                              1.20                                                                              1180                       14   0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              0.1    >19.sup.9                                                                            6.6 × 10.sup.4                                                                 10.5                                                                              1.70                                                                              1180                       15   0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              0.4      4 × 10.sup.8                                                                 6.0 × 10.sup.4                                                                 8.7 1.20                                                                              1160                       16   0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              2.0    1.1 × 10.sup.9                                                                 6.0 × 10.sup.4                                                                 8.9 1.15                                                                              1160                       17   0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              5.0    >10.sup.9                                                                            1.7 × 10.sup.3                                                                 21.0                                                                              0   1150                       18   0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              15.0   >10.sup.9                                                                            1.7 × 10.sup.3                                                                 16.1                                                                              0   1150                       19   0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              30.0   >10.sup.9                                                                            2.3 × 10.sup.4                                                                 11.5                                                                              0   1150                       *20  0.485                                                                             0.485                                                                             0.030                                                                              1.00                                                                              35.0   melt   --     --  --  --                         __________________________________________________________________________     ST* . . . Semiconductivity starting temperature                          

                                      TABLE 3                                     __________________________________________________________________________                                       Specific                                                         Minor        Resistance    Temperature                  Main Components       Component    Ω-cm    Coefficient                  Specimen                                                                           Molar Ratio of Each Component                                                                  wt %         ρ.sub.20                                                                         ρ.sub.min                                                                        %/°C.                 No.  SrO PbO 1/2(Y.sub.2 O.sub.3)                                                               TiO.sub.2                                                                         M            (at 20° C.)                                                                   (minimum)                                                                            -α                                                                          α                  __________________________________________________________________________    *1   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Mn/O         1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5                       2   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.000005                                                                             1.1 × 10.sup.4                                                                 3.4 × 10.sup.2                                                                 3.14                                                                              7.5                       3   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.00001                                                                              4.3 × 10.sup.4                                                                 9.3 × 10.sup.2                                                                 3.15                                                                              18.6                      4   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.01   1.9 × 10.sup.4                                                                 2.2 × 10.sup.3                                                                 1.62                                                                              25.9                      5   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.10   2.8 × 10.sup.5                                                                 1.1 × 10.sup.4                                                                 2.80                                                                              16.7                      6   0.497                                                                             0.497                                                                             0.006                                                                              1.00      1.2    1.8 ×  10.sup.8                                                                3.6 × 10.sup.5                                                                 3.00                                                                              11.5                     *7   0.497                                                                             0.497                                                                             0.006                                                                              1.00      1.5    >10.sup.9                                                                            >10.sup.9                                                                            --  --                       *8   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Mn/O         >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     *9   0.485                                                                             0.485                                                                             0.03 1.00      0.000005                                                                             >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     10   0.485                                                                             0.485                                                                             0.03 1.00      0.00001                                                                              >10.sup.9                                                                            5.6 × 10.sup.3                                                                 13.6                                                                              4.5                      11   0.485                                                                             0.485                                                                             0.03 1.00      0.01   >10.sup.9                                                                            4.5 × 10.sup.3                                                                 13.5                                                                              12.6                     12   0.485                                                                             0.485                                                                             0.03 1.00      1.2    >10.sup.9                                                                            4.2 × 10.sup.5                                                                 10.5                                                                              10.1                     *13  0.485                                                                             0.485                                                                             0.03 1.00      1.5    >10.sup.9                                                                            >10.sup.9                                                                            --  --                       *14  0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Cu/O         1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5                      *15  0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.000005                                                                             1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5                      16   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.00001                                                                              2.5 × 10.sup.4                                                                 4.6 × 10.sup.3                                                                 3.42                                                                              18.9                     17   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.01   7.0 × 10.sup.3                                                                 5.8 × 10.sup.5                                                                 4.24                                                                              26.4                     18   0.497                                                                             0.497                                                                             0.006                                                                              1.00      1.2    9.2 × 10.sup.6                                                                 5.8 × 10.sup.5                                                                 3.74                                                                              11.2                     *19  0.497                                                                             0.497                                                                             0.006                                                                              1.00      1.5    >10.sup.9                                                                            >10.sup.9                                                                            --  --                       *20  0.485                                                                             0.485                                                                             0.03 1.00                                                                              Cu/O         >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     *21  0.485                                                                             0.485                                                                             0.03 1.00      0.000005                                                                             >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     22   0.485                                                                             0.485                                                                             0.03 1.00      0.00001                                                                              >10.sup.9                                                                            5.6 × 10.sup.3                                                                 12.9                                                                              4.4                      23   0.485                                                                             0.485                                                                             0.03 1.00      0.01   >10.sup.9                                                                            9.8 × 10.sup.8                                                                 13.4                                                                              15.6                     24   0.485                                                                             0.485                                                                             0.03 1.00      1.2    >10.sup.9                                                                            5.2 × 10.sup.5                                                                 10.4                                                                              12.6                     *25  0.485                                                                             0.485                                                                             0.03 1.00      1.5    >10.sup.9                                                                            >10.sup.9                                                                            --  --                       26   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              V     0.01   9.2 × 10.sup.5                                                                 3.6 × 10.sup.3                                                                 4.3 22.4                     27   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Cr    0.01   8.1 × 10.sup.5                                                                 9.8 × 10.sup.2                                                                 5.6 24.4                     28   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Ni    0.01   1.2 × 10.sup.6                                                                 6.2 × 10.sup.3                                                                 4.6 23.6                     29   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Ce    0.01     2 × 10.sup.7                                                                 9.2 × 10.sup.3                                                                 4.4 25.4                     30   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Fe    0.01   3.2 × 10.sup.6                                                                 5.8 × 10.sup.3                                                                 4.7 22.7                     31   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Os    0.01   5.1 × 10.sup.5                                                                 6.5 × 10.sup.2                                                                 5.7 24.1                     32   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Ge    0.01   4.6 × 10.sup.6                                                                 1.2 × 10.sup.3                                                                 5.3 27.2                     33   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Hf    0.01   3.3 × 10.sup.6                                                                 2.5 × 10.sup.3                                                                 4.7 22.4                     *34  0.485                                                                             0.485                                                                             0.03 0.88                                                                              Co    0.01   >10.sup.9                                                                            4.2 × 10.sup.3                                                                 12.6                                                                              12.6                     35   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Sb    0.01   >10.sup.9                                                                            4.1 × 10.sup.3                                                                 13.2                                                                              12.8                     36   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Ru    0.01   >10.sup.9                                                                            4.7 × 10.sup.3                                                                 13.5                                                                              13.1                     37   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Zn    0.01   >10.sup.9                                                                            5.2 × 10.sup.3                                                                 13.4                                                                              13.2                     38   0.485                                                                             0.485                                                                             0.03 1.00                                                                              P     0.01   >10.sup.9                                                                            5.1 × 10.sup.3                                                                 13.6                                                                              13.0                     39   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Mg    0.01   >10.sup.9                                                                            3.7 × 10.sup.3                                                                 13.8                                                                              12.4                     40   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Cu + Mn                                                                             0.005 + 0.005                                                                        6.3 × 10.sup.5                                                                 2.6 × 10.sup.3                                                                 4.4 23.3                     41   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Ni + Fe                                                                             0.005 + 0.005                                                                        >10.sup.9                                                                            4.4 × 10.sup.3                                                                 13.6                                                                              12.3                     *42  0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Li/O         1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5                      *43  0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.000005                                                                             1.1 × 10.sup.5                                                                 7.1 × 10.sup.2                                                                 4.81                                                                              4.69                     44   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.00001                                                                              2.9 × 10.sup.6                                                                 2.0 × 10.sup.3                                                                 7.23                                                                              3.14                     45   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.01   6.6 × 10.sup.7                                                                 4.0 × 10.sup.3                                                                 10.5                                                                              2.54                     46   0.497                                                                             0.497                                                                             0.006                                                                              1.00      1.20   >10.sup.9                                                                            1.9 × 10.sup.4                                                                 15.5                                                                              0.47                     *47  0.497                                                                             0.497                                                                             0.006                                                                              1.00      1.5    >10.sup.9                                                                            >10.sup.9                                                                            --  --                       *48  0.485                                                                             0.485                                                                             0.03 1.00                                                                              Li/O         >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     49   0.485                                                                             0.485                                                                             0.03 1.00      0.000005                                                                             >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     50   0.485                                                                             0.485                                                                             0.03 1.00      0.00001                                                                              >10.sup.9                                                                            9.1 × 10.sup.2                                                                 18.1                                                                              1.01                     51   0.485                                                                             0.485                                                                             0.03 1.00      0.010  >10.sup.9                                                                            1.3 × 10.sup.3                                                                 27.0                                                                              0                        52   0.485                                                                             0.485                                                                             0.03 1.00      1.2    >10.sup.9                                                                            2.5 × 10.sup.5                                                                 16.0                                                                              0                        *53  0.485                                                                             0.485                                                                             0.03 1.00      1.5    >10.sup.9                                                                            >10.sup.9                                                                            --  --                       *54  0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Al/O         1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5                      *55  0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.000005                                                                             1.1 × 10.sup.4                                                                 3.7 × 10.sup.2                                                                 3.14                                                                              7.5                      56   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.00001                                                                              1.5 × 10.sup.6                                                                 7.2 × 10.sup.2                                                                 5.34                                                                              4.32                     57   0.497                                                                             0.497                                                                             0.006                                                                              1.00      0.01     6 × 10.sup.8                                                                 1.2 × 10.sup.3                                                                 13.2                                                                              3.23                     58   0.497                                                                             0.497                                                                             0.006                                                                              1.00      8.0    >10.sup.9                                                                            5.2 × 10.sup.5                                                                 11.3                                                                              0.3                      *59  0.497                                                                             0.497                                                                             0.006                                                                              1.00      10.0   >10.sup.9                                                                            >10.sup.9                                                                            --  --                       *60  0.485                                                                             0.485                                                                             0.03 1.00                                                                              Al/O         >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     *61  0.485                                                                             0.485                                                                             0.03 1.00      0.000005                                                                             >10.sup.9                                                                            3.2 × 10.sup.3                                                                 13.8                                                                              1.21                     62   0.485                                                                             0.485                                                                             0.03 1.00      0.00001                                                                              >10.sup.9                                                                            8.3 × 10.sup.2                                                                 35.0                                                                              0                        63   0.485                                                                             0.485                                                                             0.03 1.00      0.01   >10.sup.9                                                                            9.0 × 10.sup.2                                                                 38.1                                                                              0                        64   0.485                                                                             0.485                                                                             0.03 1.00      8.0    >10.sup.9                                                                            1.4 × 10.sup.5                                                                 32.0                                                                              0                        *65  0.485                                                                             0.485                                                                             0.03 1.00      10.0   >10.sup.9                                                                            >10.sup.9                                                                            --  --                       66   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              W     0.1    5.5 × 10.sup.6                                                                 1.8 × 10.sup.3                                                                 7.6 4.12                     67   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Ga    0.01   5.6 × 10.sup.6                                                                 2.8 × 10.sup.3                                                                 7.6 5.03                     68   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              In    0.01   7.2 × 10.sup.6                                                                 3.3 × 10.sup.3                                                                 8.4 4.62                     69   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Tl    0.01   6.5 × 10.sup.5                                                                 2.2 × 10.sup.2                                                                 6.6 4.44                     70   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Nb    0.01   2.8 ×  10.sup.7                                                                1.6 × 10.sup.3                                                                 8.2 4.38                     71   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Na    0.01   7.7 × 10.sup.5                                                                 1.7 × 10.sup.3                                                                 7.8 4.44                     72   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              B     0.01   6.9 × 10.sup.5                                                                 1.1 × 10.sup.3                                                                 7.7 4.33                     73   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Th    0.01   2.6 × 10.sup.7                                                                 2.6 × 10.sup.3                                                                 8.4 5.20                     74   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Ta    0.01   2.2 × 10.sup.8                                                                 2.7 × 10.sup.3                                                                 7.7 6.54                     75   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Mo    0.01   1.2 × 10.sup.6                                                                 9.5 × 10.sup.2                                                                 8.8 3.82                     76   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Ag    0.01   5.8 × 10.sup.5                                                                 1.1 × 10.sup.3                                                                 6.4 2.99                     77   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Cs    0.01     2 × 10.sup.6                                                                   1 × 10.sup.2                                                                 7.9 4.42                     78   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              Rb    0.01     3 × 10.sup.6                                                                 1.5 × 10.sup.3                                                                 10.1                                                                              4.41                     79   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Sc    0.01   >10.sup.9                                                                              7 × 10.sup.2                                                                 37.3                                                                              0                        80   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Bi    0.01   >10.sup.9                                                                              1 ×  10.sup.3                                                                28.6                                                                              0                        81   0.485                                                                             0.485                                                                             0.03 1.00                                                                              K     0.01   >10.sup.9                                                                            4.2 × 10.sup.3                                                                 42.0                                                                              0                        82   0.485                                                                             0.485                                                                             0.03 1.00                                                                              La    0.01   >10.sup.9                                                                            3.4 × 10.sup.3                                                                 44.4                                                                              0                        83   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Nd    0.01   >10.sup.9                                                                            5.6 × 10.sup.3                                                                 36.2                                                                              0                        84   0.497                                                                             0.497                                                                             0.006                                                                              1.00                                                                              W     0.05   6.3 × 10.sup.7                                                                 1.9 × 10.sup.3                                                                 8.7 0                                              Al    0.05                                              85   0.485                                                                             0.485                                                                             0.03 1.00                                                                              Li    0.05   >10.sup.9                                                                            3.2 × 10.sup.3                                                                 44.2                                                                              0                                              Nb    0.05                                              __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________                                  Specific                                                             Minor    Resistance  Temperature                         Main Components      Components                                               cm                   CoefficientMEGA.                                         Specimen                                                                           Molar Ratio of Each Component                                                                 wt. %    ρ 20                                                                            ρ min                                                                           %/°C.                                                                          ST*                         No.  SrO                                                                              PbO 1/2(Y.sub.2 O.sub.3)                                                               TiO.sub.2                                                                         SiO.sub.2                                                                        M     (at 20° C.)                                                                  (minimum)                                                                           -α                                                                          α                                                                           °C.                  __________________________________________________________________________     1   0.497                                                                            0.497                                                                             0.006                                                                              0.95                                                                              0.4                                                                              0     9.5 × 10.sup.3                                                                2.5 × 10.sup.2                                                                 3.20                                                                              7.5                                                                              1160                         2   0.497                                                                            0.497                                                                             0.006                                                                              1.2 0.4                                                                              0     1.0 × 10.sup.3                                                                8.2 × 10.sup.5                                                                 3.11                                                                              4.7                                                                              1160                         3   0.485                                                                            0.485                                                                             0.03 0.95                                                                              5.0                                                                              0     >10.sup.9                                                                           9.8 × 10.sup.2                                                                23.0                                                                              0   1150                         4   0.485                                                                            0.485                                                                             0.03 1.2 5.0                                                                              0     >10.sup.9                                                                           5.2 × 10.sup.2                                                                25.0                                                                              0   1140                         5   0.497                                                                             0.497                                                                            0.006                                                                              0.95                                                                              0  Mn 0.01                                                                             2.0 × 10.sup.3                                                                1.2 × 10.sup.1                                                                 1.70                                                                             23.8                             6   0.497                                                                            0.497                                                                             0.006                                                                              1.2 0  Mn 0.01                                                                             1.0 × 10.sup.3                                                                9.8 × 10.sup.3                                                                 1.82                                                                             22.8                             7   0.485                                                                            0.485                                                                             0.03 0.95                                                                              0  Mn 0.01                                                                             >10.sup.9                                                                             1 × 10.sup.2                                                                13.3                                                                              13.2                             8   0.485                                                                            0.485                                                                             0.03 1.2 0  Mn 0.01                                                                             >10.sup.9                                                                           2.2 × 10.sup.2                                                                14.2                                                                              13.4                             9   0.497                                                                            0.497                                                                             0.006                                                                              0.95                                                                              0  Li 0.01                                                                             1.0 × 10.sup.6                                                                3.2 × 10.sup.2                                                                 7.4                                                                               3.20                           10   0.497                                                                            0.497                                                                             0.006                                                                              1.2 0  Li 0.01                                                                             2.1 × 10.sup.5                                                                9.6 × 10.sup.1                                                                 6.8                                                                               3.44                           11   0.485                                                                            0.485                                                                             0.03 0.95                                                                              0  Li 0.01                                                                             >10.sup.9                                                                           9.5 × 10.sup.2                                                                28.1                                                                              0                               12   0.485                                                                            0.485                                                                             0.03 1.2 0  Li 0.01                                                                             >10.sup.9                                                                           2.3 × 10.sup.2                                                                30.0                                                                              0                               13   0.497                                                                            0.497                                                                             0.006                                                                              1.00                                                                              0.4                                                                              Mn 0.01                                                                             1.8 × 10.sup.4                                                                1.8 × 10.sup.3                                                                 1.70                                                                             24.8                                                                              1160                        14   0.485                                                                            0.485                                                                             0.03 1.00                                                                              5.0                                                                              Mn 0.01                                                                             >10.sup.9                                                                           4.2 × 10.sup.3                                                                19.5                                                                              12.8                                                                              1150                        15   0.497                                                                            0.497                                                                             0.006                                                                              1.00                                                                              0.4                                                                              Li 0.01                                                                               2 × 10.sup.6                                                                1.6 × 10.sup.3                                                                 7.51                                                                              3.20                                                                             1160                        16   0.485                                                                            0.485                                                                             0.03 1.00                                                                              5.0                                                                              Li 0.01                                                                             >10.sup.9                                                                           9.8 × 10.sup.2                                                                32.5                                                                              0   1140                        17   0.497                                                                            0.497                                                                             0.006                                                                              0.95                                                                              0.4                                                                              Mn 0.01                                                                               1 × 10.sup.4                                                                9.8 × 10.sup.2                                                                 1.63                                                                             22.4                                                                              1160                        18   0.497                                                                            0.497                                                                             0.006                                                                              1.2 0.4                                                                              Mn 0.01                                                                               5 × 10.sup.3                                                                  2 × 10.sup.2                                                                 1.78                                                                             21.6                                                                              1160                        19   0.485                                                                            0.485                                                                             0.03 0.95                                                                              5.0                                                                              Mn 0.01                                                                               1 × 10.sup.9                                                                  1 × 10.sup.3                                                                18.7                                                                              13.3                                                                              1150                        20   0.485                                                                            0.485                                                                             0.03 1.2 5.0                                                                              Mn 0.01                                                                             5.2 × 10.sup.8                                                                1.4 × 10.sup.2                                                                17.7                                                                              16.1                                                                              1140                        21   0.497                                                                            0.497                                                                             0.006                                                                              0.95                                                                              0.4                                                                              Li 0.01                                                                             1.5 × 10.sup.6                                                                  8 × 10.sup.2                                                                 7.55                                                                              3.14                                                                             1160                        22   0.497                                                                            0.497                                                                             0.006                                                                              1.2 0.4                                                                              Li 0.01                                                                               1 × 10.sup.6                                                                1.4 × 10.sup.2                                                                 7.70                                                                              3.50                                                                             1150                        23   0.485                                                                            0.485                                                                             0.03 0.95                                                                              5.0                                                                              Li 0.01                                                                             >10.sup.9                                                                             5 × 10.sup.2                                                                31.1                                                                              0   1140                        24   0.485                                                                            0.485                                                                             0.03 1.2 5.0                                                                              Li 0.01                                                                               8 × 10.sup.8                                                                  1 × 10.sup.2                                                                33.1                                                                              0   1140                        __________________________________________________________________________     ST* . . . Semiconductivity starting temperature                          

                                      TABLE 5                                     __________________________________________________________________________                                Specific                                          Main Components             Resistance  Temperature                           Molar Ratio of Each Component                                                 cm                          Ω                                                                       Coefficient                                       Specimen          CaO, BaO  ρ 20                                                                            ρ min                                                                           %/°C.                          No.  SrO PbO 1/2(Y.sub.2 O.sub.3)                                                               CaO + BaO                                                                            TiO.sub.2                                                                        (at 20° C.)                                                                  (minimum)                                                                           -α                                                                          α                           __________________________________________________________________________    *1   0.497                                                                             0.497                                                                             0.006                                                                              CaO                                                                              0   1.00                                                                             1.1 × 10.sup.4                                                                3.7 × 10.sup.2                                                                3.14                                                                               7.50                             *2   0.4967                                                                            0.4967                                                                            0.006                                                                              0.0050 1.00                                                                             1.1 × 10.sup.4                                                                3.7 × 10.sup.2                                                                3.14                                                                               7.50                              3   0.4965                                                                            0.4965                                                                            0.006                                                                              0.001  1.00                                                                             1.1 × 10.sup.4                                                                3.7 × 10.sup.2                                                                3.14                                                                              10.3                               4   0.492                                                                             0.492                                                                             0.006                                                                              0.01   1.00                                                                             1.1 × 10.sup.4                                                                3.7 × 10.sup.2                                                                3.11                                                                              15.5                               5   0.447                                                                             0.447                                                                             0.006                                                                              0.1    1.00                                                                             2.6 × 10.sup.5                                                                3.3 × 10.sup.3                                                                3.12                                                                              17.2                               6   0.347                                                                             0.347                                                                             0.006                                                                              0.3    1.00                                                                             7.6 × 10.sup.7                                                                1.2 × 10.sup.5                                                                3.30                                                                              18.4                              *7   0.322                                                                             0.322                                                                             0.006                                                                              0.35   1.00                                                                             >10.sup.7                                                                           >10.sup.9                                                                           --  --                                *8   0.485                                                                             0.485                                                                             0.006                                                                              0      1.00                                                                             >10.sup.9                                                                           3.2 × 10.sup.3                                                                13.8                                                                               1.21                             *9   0.4847                                                                            0.4847                                                                            0.03 0.0005 1.00                                                                             >10.sup.9                                                                           3.2 × 10.sup.3                                                                13.8                                                                               1.21                             10   0.4845                                                                            0.4845                                                                            0.03 0.001  1.00                                                                             >10.sup.9                                                                           3.2 × 10.sup.3                                                                13.8                                                                               4.02                             11   0.48                                                                              0.48                                                                              0.03 0.01   1.00                                                                             >10.sup.9                                                                           3.2 × 10.sup.3                                                                13.8                                                                              10.4                              12   0.335                                                                             0.335                                                                             0.03 0.3    1.00                                                                             >10.sup.9                                                                             5 × 10.sup.5                                                                11.7                                                                               11.20                            *13  0.31                                                                              0.31                                                                              0.03 0.35   1.00                                                                             >10.sup.9                                                                           >10.sup.9                                                                           --  --                                *14  0.497                                                                             0.497                                                                             0.006                                                                              BaO                                                                              0   1.00                                                                             1.1 × 10.sup.4                                                                3.7 × 10.sup.2                                                                3.14                                                                               7.5                              *15  0.4967                                                                            0.4967                                                                            0.006                                                                              0.0005 1.00                                                                             1.1 × 10.sup.4                                                                3.7 × 10.sup.2                                                                3.14                                                                               7.5                              16   0.4965                                                                            0.4965                                                                            0.006                                                                              0.001  1.00                                                                             1.1 × 10.sup.4                                                                3.7 × 10.sup.2                                                                3.14                                                                              10.4                              17   0.492                                                                             0.492                                                                             0.006                                                                              0.01   1.00                                                                             1.2 × 10.sup.4                                                                3.6 × 10.sup.2                                                                3.30                                                                              15.6                              18   0.335                                                                             0.335                                                                             0.006                                                                              0.3    1.00                                                                             4.8 × 10.sup.7                                                                1.2 × 10.sup.5                                                                3.40                                                                              11.3                              *19  0.322                                                                             0.322                                                                             0.006                                                                              0.35   1.00                                                                             >10.sup.9                                                                           >10.sup.9                                                                           --  --                                *20  0.485                                                                             0.485                                                                             0.03 0      1.00                                                                             >10.sup.9                                                                           3.2 × 10.sup.3                                                                13.8                                                                               1.21                             *21  0.4847                                                                            0.4847                                                                            0.03 0.0005 1.00                                                                             >10.sup.9                                                                           3.2 × 10.sup.3                                                                13.8                                                                               1.21                             22   0.4845                                                                            0.4845                                                                            0.03 0.001  1.00                                                                             >10.sup.9                                                                           3.2 × 10.sup.3                                                                14.0                                                                                5.12                            23   0.492                                                                             0.492                                                                             0.006                                                                              0.01   1.00                                                                             >10.sup.9                                                                           3.3 × 10.sup.3                                                                13.9                                                                              13.4                              24   0.347                                                                             0.347                                                                             0.006                                                                              0.3    1.00                                                                             >10.sup.9                                                                           4.3 × 10.sup.5                                                                14.0                                                                              11.2                              *25  0.322                                                                             0.322                                                                             0.006                                                                              0.35   1.00                                                                             >10.sup.9                                                                           >10.sup.9                                                                           --  --                                26   0.492                                                                             0.492                                                                             0.006                                                                              CaO                                                                              0.005                                                                             1.00                                                                             1.4 × 10.sup.4                                                                3.2 × 10.sup.2                                                                3.40                                                                              17.0                                                BaO                                                                              0.005                                                    27   0.48                                                                              0.48                                                                              0.03 CaO                                                                              0.005                                                                             1.00                                                                             >10.sup.9                                                                           2.8 × 10.sup.2                                                                15.4                                                                              14.1                                                BaO                                                                              0.005                                                    __________________________________________________________________________

                                      TABLE 6                                     __________________________________________________________________________                                         Specific                                                            Minor     Resistance    Temperature                Main Components            Components                                                                              Ω-cm    Coefficient                Specimen                                                                           Molar Ratio of Each Component                                                                       wt. %     ρ.sub.20                                                                         ρ.sub.min                                                                        %/°C.                                                                          ST*                No.  SrO PbO 1/2(Y.sub.2 O.sub.3)                                                               CaO  TiO.sub.2                                                                         SiO.sub.2                                                                         M     (at 20° C.)                                                                   (minimum)                                                                            -α                                                                          α                                                                           °C.         __________________________________________________________________________     1   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           0.95                                                                              0.4    0    8 × 10.sup.3                                                                 7.8 × 10.sup.2                                                                 2.88                                                                              18.0                                                                              1160                2   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.2 0.4    0  1.0 × 10.sup.3                                                                 5.2 × 10.sup.1                                                                 3.32                                                                              17.2                                                                              1160                3   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           0.95                                                                              5.0    0    1 × 10.sup.9                                                                 5.8 × 10.sup.2                                                                 20.4                                                                              11.3                                                                              1150                4   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.2 5.0    0    7 × 10.sup.8                                                                 1.2 × 10.sup.2                                                                 1.70                                                                              31.5                                                                              1140                5   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.2 0      0  1.1 × 10.sup.3                                                                 5.2 × 10.sup.9                                                                 3.12                                                                              16.8                    6   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           0.95                                                                              0      0  7.8 × 10.sup.3                                                                   1 × 10.sup.3                                                                 14.4                                                                              10.4                    7   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.2 0      0  >10.sup.9                                                                            2.4 × 10.sup.2                                                                 15.3                                                                              10.0                    8   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           0.95                                                                              0   Mn 0.01                                                                             1.2 × 10.sup.4                                                                   1 × 10.sup.3                                                                 1.58                                                                              32.3                    9   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.2 0   Mn 0.01                                                                             7.8 × 10.sup.3                                                                   5 × 10.sup.2                                                                 1.65                                                                              34.4                   10   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           0.95                                                                              0   Mn 0.01                                                                             >10.sup.9                                                                              1 × 10.sup.3                                                                 13.4                                                                              17.6                   11   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.2 0   Mn 0.01                                                                               6 × 10.sup.8                                                                 2.1 × 10.sup.2                                                                 14.4                                                                              30.0                   12   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           0.95                                                                              0   Li 0.01                                                                             1.2 × 10.sup.6                                                                 9.4 × 10.sup.2                                                                 7.77                                                                              12.4                   13   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.2 0   Li 0.01                                                                             5.8 × 10.sup.5                                                                 4.3 × 10.sup.2                                                                 8.02                                                                              13.2                   14   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           0.95                                                                              0   Li 0.01                                                                             >10.sup.9                                                                              1 × 10.sup.3                                                                 23.4                                                                              8.1                    15   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.2 0   Li 0.01                                                                               6 × 10.sup.8                                                                 3.2 × 10.sup.2                                                                 26.0                                                                              7.9                    16   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.00                                                                              0.4 Mn 0.01                                                                             2.1 × 10.sup.4                                                                 1.5 × 10.sup.3                                                                 1.72                                                                              31.2                                                                              1160               17   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.00                                                                              5.0 Mn 0.01                                                                             >10.sup.9                                                                            3.5 × 10.sup.3                                                                 18.8                                                                              17.9                                                                              1140               18   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.00                                                                              0.4 Li 0.01                                                                             3.1 × 10.sup.6                                                                 1.4 × 10.sup.2                                                                 7.20                                                                              10.8                                                                              1160               19   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.00                                                                              5.0 Li 0.01                                                                             >10.sup.9                                                                            1.4 × 10.sup.2                                                                 29.2                                                                              7.8 1140               20   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           0.95                                                                              0.4 Mn 0.01                                                                               1 × 10.sup.4                                                                 1.1 × 10.sup.3                                                                 1.62                                                                              34.4                                                                              1160               21   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.2 0.4 Mn 0.01                                                                               6 × 10.sup.3                                                                 4.8 × 10.sup.2                                                                 1.48                                                                              35.2                                                                              1160               22   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           0.95                                                                              5.0 Mn 0.01                                                                               1 × 10.sup.9                                                                 1.2 × 10.sup.3                                                                 17.7                                                                              19.2                                                                              1150               23   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.2 5.0 Mn 0.01                                                                             7.2 × 10.sup.8                                                                 5.2 × 10.sup.2                                                                 18.4                                                                              20.4                                                                              1140               24   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           0.95                                                                              5.0 Li 0.01                                                                             9.5 × 10.sup.5                                                                 5.2 × 10.sup.2                                                                 8.12                                                                              11.8                                                                              1160               25   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.2 0.4 Li 0.01                                                                               2 × 10.sup.5                                                                 1.1 × 10.sup.2                                                                 7.92                                                                              13.2                                                                              1150               26   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           0.95                                                                              5.0 Li 0.01                                                                             >10.sup.9                                                                              5 × 10.sup.3                                                                 30.0                                                                              10.1                                                                              1160               27   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.2 5.0 Mn 0.01                                                                             5.4 × 10.sup.2                                                                   3 × 10.sup.2                                                                 31.2                                                                              12.2                                                                              1140               28   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.00                                                                              0.4    0  1.0 × 10.sup.4                                                                 2.8 × 10.sup.2                                                                 3.28                                                                              14.8                                                                              1160               29   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.00                                                                              5.0    0  >10.sup.9                                                                            1.9 × 10.sup.3                                                                 22.3                                                                              11.1                                                                              1150               30   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.00                                                                              0   Mn 0.01                                                                             2.2 × 10.sup.4                                                                 1.9 × 10.sup.3                                                                 1.66                                                                              30.4                   31   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.00                                                                              0   Mn 0.01                                                                             >10.sup.9                                                                            3.8 × 10.sup.3                                                                 14.2                                                                              18.8                   32   0.492                                                                             0.492                                                                             0.006                                                                              CaO 0.01                                                                           1.00                                                                              0   Li 0.01                                                                             3.2 × 10.sup.6                                                                 1.8 × 10.sup.3                                                                 7.44                                                                              11.2                   33   0.48                                                                              0.48                                                                              0.03 CaO 0.01                                                                           1.00                                                                              0   Li 0.01                                                                             >10.sup.9                                                                            2.4 × 10.sup.3                                                                 25.4                                                                              7.8                    __________________________________________________________________________     ST* . . . Semiconductivity starting temperature                          

TABLE 1 indicates that compositions containing TiO₂ of less than 0.90mol or more than 2.0 mol are increased in resistance to a degreesufficient to render them impractical, as apparent from test results ofthe compositions of Specimens Nos. 1, 8, 9, 16, 17 and 31. An increasein amount of TiO₂ causes specific resistance or resistivity ρ_(min) tobe moved upwardly without varying -α and α or a gradient of atemperature coefficient, as seen from Specimens Nos. 3 to 7 and Nos. 13to 15. Test results on Specimens Nos. 18 to 23, Nos. 26 to 29 and Nos.32 to 35 indicate that an increase in Y₂ O₃ which is an additive forsemiconductivity causes each composition to exhibit CTR characteristicsrather than V-type PTC characteristics, and Specimens Nos. 13 to 15indicate that an increase in TiO₂ as well as that in Y₂ O.sub. 3 leadsto movement of the resistivity from a lower level to a high levelwithout varying the temperature coefficients -α₁ and α. Specimens Nos.38 to 42, Nos. 45 to 47 and Nos. 50 to 52 possess V-type PTCcharacteristics and each indicate that an increase in Sr and a decreasein Pb result in a curie point Tc of each composition being substantiallymoved toward a negative side. Specimens Nos. 55 to 59, Nos. 62 to 64 andNos. 67 to 69 each possess CTR characteristics and have a curie point Tcsubstantially moved toward a negative side, so that the curie point Tcmay be controlled over a wide range extending to the vicinity of a curiepoint of each of simple substances SrTiO₃ and PbTiO₃. A content of Pbmore than 0.85 mol or less than 0.05 mol in the composition increasesits resistance to a degree sufficient to render the compositionimpractical. In compositions of Specimens Nos. 71 to 81, rare earthelements are used as R. It will be noted that each of the rare earthelements exhibits substantially the same behavior as Y₂ O₃ used inSpecimens Nos. 1 to 70. FIG. 1 shows relationships between resistivityand a temperature in some representatives of the specimens shown inTABLE 1.

The compositions shown in TABLE 2 each were prepared so as to containSrO, PbO and TiO₂ as a main component and SiO₂ as a minor component. InTABLE 2, Specimens Nos. 3 to 9 and Nos. 13 to 19 each indicate that itis substantially varied in -α with an increase in addition of SiO₂, sothat characteristics of the composition are changed from V-typecharacteristics to CTR characteristics when a content of SiO₂ is 2.0 wt%or more, resulting in its semiconductivity starting temperature ST beinglowered by 20° to 50° C. This means that an optimum temperature for thefiring is likewise lowered, leading to energy savings and massproduction of the composition at significantly reduced costs. A contentof SiO₂ below 0.001 wt% fails to cause the semiconductivity startingtemperature to be lowered, whereas when SiO₂ is contained at a level of30 wt% or more in the composition, the composition is not provided withsemiconductivity, resulting in being melted during firing. An experimentrevealed that a quantitative range of each of SrO, PbO, Y₂ O₃ and TiO₂in TABLE 2 is substantially the same as that in TABLE 1 irrespective ofaddition of SiO₂. FIG. 2 shows relationships between resistivity and atemperature in some representatives of the specimens shown in TABLE 2.

The compositions shown in TABLE 3 each were prepared so as to containSrO, PbO and TiO₂ as a main component and M as a minor component. M isat least one material selected from the group consisting of Mn, Cu, Cr,Ni, Fe, Co, Ru, Os, Ge, Hf, P, Sb, V, Mg, Zn, W, Al, Mo, In, Ga, Nb, Ta,Bi, Sc, rare earth elements, Th, Na, K, Li, B, Ag, Cs and Rb. In each ofthe compositions, the amount of M is varied while keeping the amount ofY₂ O₃ at a typical level sufficient to permit it to exhibit V-typecharacteristics and CTR characteristics. As will be noted from SpecimensNos. 3 to 6, Nos. 10 to 12, Nos. 16 to 13 and Nos. 22 to 24, Mh and Cucontributes to an increase in temperature coefficient α of thecomposition to enhance the PTC characteristics. However, the amount of Mbelow 0.00001 wt% fails to permit the composition to exhibit suchadvantages and M in an amount above 1.2 wt% increases resistance of thecomposition to a degree sufficient to render it impractical. SpecimensNos. 26 to 39 relate to addition of V, Cr, Ni, Ce, Fe, Os, Ge, f, Co,Sb, Ru, Zn, P and Mg, respectively. Each of the elements exhibitssubstantially the same advantage as Mn and Cu.

Specimens Nos. 40 and 41 each were prepared so as to contain two kindsof elements simultaneously added. It will be noted that the combinedaddition of the elements exhibits substantially the same advantage asdescribed above.

An experiment indicated that a quantitative range of each of SrO, PbO,Y₂ O₃ and TiO₂ in TABLE 3 is substantially the same as that in TABLE 1irrespective of addition of the M. Li, Al, W, Ga, In, Tl, Nb, Na, B, Th,Ta, Mo, Ag, Cs, Rb, Sc, Bi, K, La, Nd and rear earth elements except Ceeach contributes to an increase in temperature coefficient -α of thecomposition, resulting in the NTC characteristics being emphasized, asapparent from Specimens Nos. 45 to 44, Nos. 51 to 53, Nos. 57 to 59,Nos. 63 to 65 and Nos. 67 to 83. A content of each component below0.0001 wt% falls to exhibit any effect and the content of 1.2 wt% ormore (8 wt% or more in the case of Al) causes resistance of thecomposition to be increased to a degree sufficient to render itimpractical. A combination of the M such as, for example, W, Al, Li+ Nbor the like likewise leads to an increase is temperature coefficient -α,as noted from Specimens Nos. 84 and 85.

FIGS. 3 and 4 each show relationships between resistivity and atemperature in some representatives of specimens shown in TABLE 3.

The compositions shown in TABLE 4 each were prepared so as to containSrO, PbO and TiO₂ as a main component and SiO₂ and M as a minorcomponent. TABLE 4 indicates that concurrent or combined addition ofSiO₂ and M exhibits a combination of advantages obtained by adding thecomponents independent from each other.

In TABLE 4, Specimens Nos. 1 to 4 indicate advantages obtained due to anincrease in TiO₂ and addition of SiO₂. More specifically, addition ofSiO₂ causes a semiconductivity starting temperature of the compositionto be lowered and an increase in TiO₂ permits resistance of thecomposition to be adjusted without significantly varying its temperaturecoefficients α and -α.

Specimens Nos. 5 to 12 indicate advantages due to an increase in TiO₂and addition of M. Addition of Mn or Li causes a semiconductivitystarting temperature of the composition to be lowered and an increase inTiO₂ permits its resistance to be adjusted without significantly varyingits temperature coefficients α and -α.

Addition of M other than Li and Mn exhibits like advantages.

Specimens Nos. 13 to 16 indicate advantages due to combined addition ofSiO₂ and M while keeping the amount of TiO₂ at a constant level. It willbe noted that Mn and Li enhance PTC characteristics and NTCcharacteristics of the composition, respectively, and addition of SiO₂leads to lowering of the semiconductivity starting temperature. Also,addition of M other than Mn and Li exhibits like advantages.

Specimens Nos. 17 to 24 indicate advantages due to an increase in TiO₂and combined or concurrent addition of SiO₂ and M. Mn and Li enhance PTCcharacteristics and NTC characteristics of the composition,respectively, and addition of SiO₂ leads to lowering of thesemiconductivity starting temperature. TiO₂ permits resistance of thecomposition to be adjusted. Also, addition of M other than Mn and Liexhibits like advantages.

An experiment proved that a quantitative range of each of SrO, PbO, Y₂O₃ and TiO₂ in TABLE 4 is substantially the same as that in TABLE 1irrespective of combined addition of SiO₂ and M.

The compositions shown in TABLE 5 each were prepared so as to containSrO, PbO and TiO₂ as a main component wherein a part of each of SrO andPbO is replaced with CaO, BaO or CaO+BaO to cause the composition toexhibit V-type PTC characteristics or CTR characteristics. Moreparticularly, Specimens Nos. 3 to 6, Nos. 10 to 12, Nos. 16 to 18 andNos. 22 to 24 indicate that addition of CaO or BaO causes thecomposition to exhibit enhanced PTC characteristics (α). Also, it wasobserved that each of the specimens exhibits a substantially uniformparticle size or diameter in the form of a fired element. For example,an analysis of distribution of particle diameter carried out by means ofa photograph of a surface of an element obtained by subjecting SampleNo. 1 in TABLE 5 to firing revealed that its has an average particlediameter of 13.2μ with a standard deviation of 4.1μ, whereas a similaranalysis on an element having CaO and BaO added thereto indicates astandard deviation of 2μ in a similar average particle diameter. Thus,it will be noted that addition of CaO, BaO or CaO+BaO contributes touniformalizing of the particle size, resulting in reducing a variationof characteristics of the composition.

Specimens Nos. 26 and 27 indicate that concurrent or combined additionof CaO and BaO likewise exhibits substantially the same advantage asdescribed above. However, it was found that the advantage is notexhibited at a content of CaO or BaO below 0.0005 mol and the content of0.3 mol or more causes an increase in resistance to a degree sufficientto render the composition impractical. Also, an experiment revealed thata quantitative range of each of SrO, PbO, Y₂ O₃ and TiO₂ in TABLE 5 issubstantially the same as that in TABLE 1 irrespective of concurrentaddition of CaO and BaO. FIG. 5 shows relationships between resistivityand a temperature in some representatives of the specimens shown inTABLE 5.

The compositions shown in TABLE 6 each were prepared so as to containSrO, PbO and TiO₂ as a main component and SiO₂ and M as a minorcomponent. TABLE 6 indicates that concurrent or combined addition ofSiO₂ and M exhibits a combination of advantages obtained by adding thecomponents independent from each other. In TABLE 6, CaO is added to allspecimens, resulting in the PTC characteristics being somewhat enhancedand the grain or particle size being rendered uniform. To thecompositions of Specimens Nos. 8 to 10, 12, 14 and 30 to 33 is addedonly M. It will be noted that Mn increases a temperature coefficient -αof the composition and enhances the NTC characteristics. The testresults on the compositions of Specimens Nos. 5 and 7 indicate that anincrease in amount of TiO₂ permits the resistance to be adjusted.Specimens Nos. 1, 3, 28 and 29 indicate that addition of SiO₂ causes asemiconductivity starting temperature of the composition to be loweredand Specimens Nos. 2 and 4 indicate that addition of SiO₂ lowers thesemiconductivity starting temperature and an increase in TiO₂ permitsadjustment or control of the resistance.

Also, in TABLE 6, Specimens Nos. 9, 11, 13 and 15 reveal advantages dueto an increase in TiO₂ and addition of M. More specifically, Mn and Licontribute to enhancement of the PTC characteristics and NTCcharacteristics, respectively, and TiO₂ permits adjustment of theresistance. It was found that M other than Mn and Li exhibitssubstantially the same advantage. Specimens Nos. 16 to 20, 22, 24 and 26indicate test results of combined addition of SiO₂ and M. It will benoted that Mn and Li enhance the PTC characteristics and NTCcharacteristics respectively, and SiO₂ contributes to lowering of thesemiconductivity starting temperature. Specimens Nos. 21, 23, 25 and 27reveals advantages due to an increase in TiO₂ and combined addition ofSiO₂ and M. Mn and Li enhance the PTC characteristics and NTCcharacteristics, SiO₂ contributes to lowering of the semiconductivitystarting temperature, and an increase in TiO₂ permits adjustment of theresistance. Addition of M other than Mn and Li exhibits substantiallythe same advantage. Also, it was found that this is true of addition ofBaO in place of CaO or concurrent addition of BaO and CaO.

Also, it was confirmed by an experiment that a quantitative range ofeach of SrO, PbO, Y₂ O₃ and TiO₂ in TABLE 6 is substantially the same asthat in TABLE 1 irrespective of combined addition of SiO₂ and M.

As can be seen from the foregoing, in the semiconductive ceramiccomposition of the present invention which contains a main componentconsisting of SrO, PbO and TiO₂, a variation of TiO₂ permits specificresistance or resistivity of the composition to be varied withoutsignificantly varying the resistance-temperature characteristics. Also,addition of SiO₂ permits the semiconductivity starting temperature to bedecreased by 20° to 50° C., resulting in improving sintering of thecomposition and facilitating manufacturing of the composition. SiO₂ inan amount below 2.0 wt% causes the composition to exhibit V-type PTCcharacteristics and the addition in amount of 2.0 wt% or more leads tochange of characteristics of the composition from NTC characteristics tocharacteristics approaching to CTR characteristics. Also, thecomposition of the present invention has an advantage capable ofsubstantially moving a point at which resistance is suddenly varied, ascompared with the prior art which merely causes slight movement of thepoint. Also, a variation in addition of SiO₂ and Y₂ O₃ causescharacteristics of the composition to be varied as desired. Moreparticularly, it permits characteristics of the composition to bechanged from PTC characteristics to V-type PTC characteristics andfurther to characteristics approaching to CTR characteristics.

Addition of Ca or Ba renders a particle side of the compositionsubstantially uniform, resulting in massproduction of the compositionstable in quality and free of a variation in characteristics. Additionof M which is an impurity contributes to control and improvement ofvarious characteristics of the composition. For example, addition of atleast one of Mn, Cu, Cr, Ni, Ce, Fe, Co, Ru, Os, Ge, Hf, P, Sb, V, Mgand Zn contributes to an improvement in rise of PTC characteristics andaddition of at least one of W, Al, Mo, In, Ga, Nb, Ta, Bi, Sc, rareearth elements (except Ce), Th, Na, K, Li, B, Ag, Cs and Rb renders agradient of NTC characteristics steep.

Thus, it will be noted that the semiconductive ceramic composition ofthe present invention exhibits various kinds of resistance-temperaturecharacteristics and is readily manufactured on a large scale.

While the present invention has been described with a certain degree ofparticularity with reference to the example and drawings, obviousmodifications and variations are possible in the light of the aboveteachings. It is therefore to be understood that within the scope of theappended claims, the invention may be practiced otherwise than asspecifically described.

What is Claimed is:
 1. A semiconductive ceramic composition comprisingSr of 0.05 to 0.95 mol based on SrO, Pb of 0.05 to 0.85 mol based onPbO, Ti of 0.90 to 2.0 mol based on TiO₂ and R of 0.001 to 0.3 mol basedon its oxide, wherein R is at least one material selected from the groupconsisting of rare earth elements, Bi, V, W, Ta, Nb and Sb, and theamounts of Bi, Sb and rare earth elements except Ce, are based on 1/2(R₂O₃), the amounts of V, Ta and Nb are based on 1/2(R₂ O₅) and the amountsof Ce and W are based on RO₂ and RO₃, respectively, and subjected tofiring in an oxidizing atmosphere.
 2. A semiconductive ceramiccomposition as defined in claim 1 further comprising SiO₂ added in anamount of 0.001 to 30 wt%.
 3. A semiconductive ceramic composition asdefined in claim 1 further comprising SiO₂ added in an amount of 0.001to 30 wt% and M;said M being at least one material selected from thegroup consisting of Mn, Cu, Cr, Ni, Fe, Co, Ru, Os, Ge, Hf, P, Sb, V,Mg, Zn, W, Al, Mo, In, Ga, Nb, Ta, Bi, Sc, rare earth elements, Th, Na,K, Li, B, Ag, Cs and Rb; said M being added in amounts of 0.00001 to 1.2wt% except Al and W; Al and W being added in amounts of 0.00001 to 8wt%.
 4. A semiconductive ceramic composition as defined in claim 1,wherein SrO and PbO in amounts of 0.001 to 0.3 mol are replaced with atleast one of BaO and CaO.
 5. A semiconductive ceramic composition asdefined in claim 4 further comprising SiO₂ added in an amount of 0.001to 30 wt%.
 6. A semiconductive ceramic composition as defined in claim 4further comprising M;said M being at least one material selected fromthe group consisting of Mn, Cu, Cr, Ni, Fe, Co, Ru, Os, Ge, Hf, P, Sb,V, Mg, Zn, W, Al, Mo, In, Ga, Nb, Ta, Bi, Sc, rare earth elements, Th,Na, K, Li, B, Ag, Cs and Rb; said M being added in amounts of 0.00001 to1.2 wt% except Al and W; Al and W being added in amounts of 0.00001 to 8wt%.
 7. A semiconductive ceramic composition as defined in claim 4further comprising SiO₂ added in an amount of 0.001 to 30 wt% and M;saidM being at least one material selected from the group consisting of Mn,Cu, Cr, Ni, Fe, Co, Ru, Os, Ge, Hf, P, Sb, V, Mg, Zn, W, Al, Mo, In, Ga,Nb, Ta, Bi, Sc, rare earth elements, Th, Na, K, Li, B, Ag, Cs and Rb;said M being added in amounts of 0.00001 to 1.2 wt% except Al and W; Aland W being added in amounts of 0.00001 to 8 wt%.
 8. A semiconductorceramic composition comprising:Sr in the amount of 0.05 to 0.95 molbased on SrO, Pb in the amount of 0.05 to 0.85 mol based on PbO, Ti inthe amount of 0.90 to 2.0 mol based on TiO₂, and R in the amount of0.001 to 0.3 mol based on its oxide, wherein R is at least one materialselected from a group consisting of rare earth elements, V, Ta, Nb, Sb,and Bi, wherein the amount of the rare earth element except for Ce andthe amount of Sb and Bi are based on 1/2(R₂ O₃), the amounts of V, Taand Nb are based on 1/2(R₂ O₅), the amount of Ce is based on RO₂, andthe amount of W is based on RO₃, the above elements of the compositionare mixed with an additive M before firing in an oxidizing atmosphere toproduce the semiconductor ceramic composition, wherein M is selectedfrom a group consisting of Mn, Cu, Cr, Ni, Fe, Co, Ru, Os, Ge, Hf, P,Sb, V, Mg, Zn, W, Al, Mo, In, Ga, Nb, Ta, Bi, Sc, rare earth elements,Th, Na, K, Li, B, Ag, Cs, and Rb; said M being added in amounts of0.00001 to 1.2 wt% except for Al and W, and Al and W being added inamounts of 0.00001 to 8 wt%.
 9. A semiconductive ceramic composition asdefined in claim 8, wherein SrO and PbO in amounts of 0.001 to 0.3 molare replaced with at least one of BaO and CaO.
 10. A semiconductiveceramic composition as defined in claim 8 further comprising SiO₂ addedin an amount of 0.001 to 30 wt%.